Blood
by PteraWaters
Summary: After an unsettling biology project, Allison learns that her parents can't be her parents. She runs away for a night and soon learns which family's blood really flows through her veins. Slight Stiles/Derek.


In which Allison is a Hale It starts with her final project for Biology class. Ms. Laughlin gave her students a choice of projects and Allison just has to pick the genetics one. Why can't she have picked the botany project? She could be working on a presentation about roses or tomato plants instead of systematically proving that her parents _can't _be her parents. The eye and hair colors are one thing, but the blood type can't be explained away.

Allison can't be Victoria and Christopher Argent's daughter. Maybe one, but not both. She denies the results for a long time, going so far as to steal three extra typing kits from the biology lab and donating blood to the local blood bank, just in case the school-grade tests are wrong.

They're not.

Allison gets a card from the blood bank and scratches at the bandage in the crook of her elbow as she stares at it. O-positive. The people Allison thought were her parents both had negative genotypes. She _cannot_be their daughter. That's not even mentioning the fact that Chris' blood type is AB. Doubly impossible.

Allison wonders if this is what Jackson felt like when he learned he was adopted.

Oh, God! Allison was _adopted_! She could have family out there somewhere! Family who aren't hunters, family who value Allison's ability to take pictures and paint (sort of really badly) as well as her skill with a bow! She has to _find them_!

Allison doesn't bother going home. She doesn't want to bother anyone else with this or delve into research yet, either. Mostly she just wants to think about her new identity and puzzle over questions on her own before she brings them to anyone else.

She also wants to cry where no one will hear her, because Allison is not a crier. She just ... _can't quite_hold in all of her emotions at the moment and some of it has to escape.

So does she.

She drives to the Preserve and parks when the road ends. She ties her scarf around her neck tighter against the chill and sets off in a random direction. It doesn't matter where she's going except away, where her supposed father won't be able to find her until she wants to be found.

Around sunset, Allison finds the lee side of a large boulder and enough dry wood to start a small fire. She may be in the midst of an emotional crisis, but that doesn't mean she'll be stupid and freeze to death out of spite. She made sure her lighter worked before she drove out of town. It's too cold to sleep, but the embers of the fire feel nice next to her feet and hands, so maybe Allison does doze a little in the small hours of the night.

A snap of a twig and footsteps that seem deliberately too loud rouse Allison from drowsing to hyper aware and she notches an arrow in her bow. As she draws back, ready to fire if need be, Stiles' voice calls out, "Allison? Allison, where are you?"

Allison doesn't reply, quietly kicking dirt onto the remains of her campfire so Stiles won't see the smoke. She moves, three steps ahead of him and always out of sight.

"Allison! Come on! I know you're out here! Everyone just wants to make sure you're okay and not, like, bear food or something."

Realizing that if she doesn't assure Stiles that she's fine, but just doesn't want to talk to anyone, that he'll call up his father and the search dogs, Allison steps out from behind a tree. "How did you find me?" she asks, bow still in her hand, but aimed at the ground, not Stiles. "You must have had help. But Scott's in Illinois until Tuesday."

"Derek," Stiles replies with half a shrug before taking a few careful steps toward her like he's afraid she might spook. "He, uh, he didn't want to upset you or whatever, so he called me."

"Good call," Allison says, putting away her arrow and slinging the bow over her shoulder. "_You_didn't murder my–" Allison stops herself short, shaking her head. Victoria Argent may not have been her mother. Or maybe she was and Allison lost all of the blood family she knew when Derek bit her.

Stiles looks like he wants to argue that Derek didn't kill Victoria either, but he snaps his mouth shut before any words come out. He must have heard from Scott just how well that argument had gone over with Allison, who had been _so sure_her mother didn't deserve what had happened to her. Instead of arguing Stiles just gives her this intensely sympathetic look that makes Allison look away from him and huff. It's the hand on her shoulder that breaks Allison's resolve and she lets herself turn against Stiles' chest and cry. She came out here to cry and hadn't yet, so finally releasing the tears she's held onto all night is more than cathartic.

Stiles hugs Allison and holds her until she can pull herself together, relieved, but also embarrassed that anyone else saw her weakness. She does say, "Thank you," though, because she means it.

"Hey, no problem," Stiles replies, his tone carefully comedic, like he's trying to make her laugh. "I do this all the time, like when Scott stubs his toe or remembers he's not as awesome as he thinks he is."

Allison does laugh, because she's fairly sure Scott has never sobbed through Stiles' shirt. The image that springs to her mind is so over dramatic that she giggles at the thought of Scott flopping around under the pressure of his intense man pain. "Or when I break up with him again?" she asks with a smile, which Stiles returns.

"Totally." Stiles squeezes her arm and pulls Allison into another hug so they aren't eye-to-eye when he asks, "So do you want to tell me why you ran away?"

"I figured something out," she says, knowing she's testing the waters to gauge Stiles' reaction. When he just hums and lets her slip out of his arms to stand next to him, looking down at her hands, Allison elaborates. "I figured out my parents can't be my parents."

The gasp that comes out of Stiles is so over the top and out of place that Allison has to raise her eyebrow in his direction until he scratches the back of his neck and apologizes. "Sorry!" He wavers for a few more seconds before asking, "So you're, what? Adopted?"

"I guess," Allison nods, hugging one of her arms with the other. "But I don't get _why_a family of hunters would do that? Why would they adopt someone into this life? I could have been perfectly normal."

"Dude, no one's perfectly normal," Stiles says, which makes Allison look over to see him chewing on his thumbnail. "But I get what you mean. Maybe they couldn't have kids and wanted to have someone to pass the knowledge on? I mean, I know after I was born, my parents couldn't have any more kids. They were starting to talk about adopting me a little brother or sister when my mom's cancer came back. People have their reasons. That doesn't mean they don't – didn't love you."

"I suppose," Allison nods, fidgeting with the hem of her coat. The adrenaline has been ebbing away for a few minutes, allowing the cold to seep back into her bones. She shivers. "I just– I thought I knew all the family secrets by now. Hunting. What Kate did. Gerard. I mean, what's next?"

Stiles shrugs. "You could always find out you have a long-lost twin sister who was kidnapped from the hospital as a baby."

There's something about the way he says it that makes Allison think he's not just pulling this out of his ass or from a Telenovela he saw once. She frowns at him and asks, "Who?"

"What? _No one_!" Stiles gets shifty-eyed and tries to wander away, but Allison darts forward and grabs him by the collar. "He's way older than you! It's not like you're secretly twenty-two and are posing as a high schooler or anything!"

Allison frowns. "My parents made me take the sixth grade twice and I was already lots taller than all the other girls. I ... think I remember having two or three five-years-old birthday parties. All this time I thought I was just remembering wrong. Oh, my god!" Allison feels like her entire body is shaking and her vision goes gray. "What if I'm twenty-two? What if my- well, if _they_kidnapped me? Stiles!"

"Hey, hey," Stiles replies, manually unclenching Allison's fist from his shirt. "I don't know what I'm talking about, okay? Just breathe." He holds her close and Allison can feel Stiles' ribs expanding with intent. "Breathe with me. In. Out."

But Allison can't even breathe in, not with Stiles holding her, caging her in. She tries and she tries, but it's like when she fell out of that apple tree in fifth grade (she was thirteen!) and landed on her back and couldn't get her lungs to work for sixty terrifying seconds. She's going to die. Then it hits her that she knows what to do. She looked it up after the apple tree and knows that she has to crouch down and put her head between her knees and that will work.

It has to work.

Allison hits Stiles' shoulder until he lets go and crouches down, releasing the pressure and taking a giant, whooping breath of air that tastes like rotting leaves and earthworms. "Oh, God," she moans, panting and willing the ache in her stomach to go away. "Oh, my God! Stiles!"

He's already crouching down beside her, a hand on her shoulder as he says, "I am _so_freaking sorry I said anything. Seriously. And it's probably not even relevant to this situation. Oh, man."

"Who?" Allison asks again, this time through gritted teeth. "Who do you know that lost their twin sister?"

"Uhhh..." Stiles drags out his non-reply like he's stalling for time. Which he must be. "Maybe, _possibly_, Derek Hale?"

Allison can't believe Stiles is serious. Derek is a born werewolf. His patents were werewolves, his dead sister was one, and Allison... is not. "What? That's stupid. I'm not a werewolf!"

"His twin was human," Stiles says through clenched teeth, his mouth open in a rictus of regret or something. Allison hopes he beats himself up a lot over this incident.

In fact, she's going to beat him up a lot over this incident, starting with a swift slap the back of his head. Ignoring Stiles' noise of protest, Allison says, "Nope. It's not true. I'm eighteen years old and my mother was Victoria Argent and she had an affair with the milkman and," she narrows her eyes at Stiles, studying him for half a moment before asking, "why did Derek tell you that?"

"What?" Stiles asks, hand dropping from where he's been rubbing his head.

"Derek never tells anyone anything," Allison pointed out. "Why would he tell you about his sister?"

Flustered, Stiles makes a few half words until finally he says, "Because he was trying to _convince_me that hunters were bad dudes. Like, the kind of dudes that stole newborns with minor heart conditions from the hospital, just because her parents were werewolves."

Allison doesn't believe Stiles for a hot minute. For a guy who lies all the time, she doesn't think Stiles is very good at it. Not when Allison grew up with some of the best liars in the country.

She steps a little closer, leaning up onto her toes a little to look Stiles straight in the eye. "Why ... did he tell you? Did he know it was me? Does he know it's not me? Did he send you here to convince me I'm his sister so I'll stop trying to kill him?"

Allison's voice grew progressively louder as she questioned Stiles and he winced. "I-I think you're overestimating Derek's deviousness. Really, he's as straightforward as a game of tic-tac-toe. Most of the cool ideas are mine, actually, and–"

Not nearly in the mood to put up with Stiles rambling, Allison lets go of him and slides back into her heels before sashaying away. "Fine, then. I'll have to go find him myself and ask him."

Before Allison gets very far, Derek steps out from behind a tree. Of course he was here, and listening. Stiles had told her he was acting as Derek's voice after she'd already been found by the werewolf.

There is no way Derek is her _brother_. Allison is an only child. She always has been and she always will be. If she can just get Derek to give her a small blood sample, she can prove it. Right? Or, maybe she won't be able to work it out with a sibling, but no parent sample. Allison can't think right now, but she is going to prove that she isn't related to Derek Hale, if it was the last thing she does.

But first, she has to find him. He can;t be far. Maybe within hearing distance. "Derek! Derek!" she calls, stomping forward through the forest. "Where are you?"

"Here," a voice says from entirely too close and Allison hates herself for flinching a little at the noise. She _knew _he was close, he shouldn't have been able to surprise her like that. Allison turns to face him, frowning at the way Derek's usual surliness had been replaced with eyebrows raised in concern, like now that there was the slightest chance imaginable she could be his long-lost sister that changed everything for him. It doesn't change the fact that he is the reason the woman Allison had known as her mother is dead.

Allison crosses her arms over her chest and says, "I don't believe it."

"My parents told us it was hunters who had taken her," Derek says carefully, like he doesn't quite want to imply what he's implying. Allison also notes that he doesn't say, "you," he says, "her," like he doesn't want it to be true either. Well, fine. Allison doesn't need any of this. It's just ... she needs to _know_.

"What's your blood type?" she asks, hoping Derek would have found out at some point. And that it will actually mean something once he tells her.

"Werewolf," he replies, like that is the end of the story.

Allison huffs. "That's not a blood type. Something like A-negative or O-positive. Not just _werewolf_!"

"I'm not human," Derek replies, his scowl deepening. "When we had to do those card tests in bio class, my parents wouldn't sign the permission slip. My blood reacts differently."

Allison scowls right back at him. Stupid Derek acting like he knows everything, when it's clear to everyone else that he doesn't. "Well, how are you going to prove it?"

Derek pulls his wallet out of his back pocket and takes a picture out of it, stepping close enough to hand it to Allison. "This is a picture of my mother," he says as she takes it. "I wasn't looking for a resemblance before, but now..."

Allison looks down at the picture and sees a woman with dark hair and eyes. She looks vaguely Hispanic, or maybe Native American, but what really catches Allison's eye are her nose and cheekbones. The same nose and cheekbones Allison has been staring at in the mirror all her life. And there, in the background of the picture and out of focus, is Derek. Younger Derek, probably only thirteen or fourteen at the time. When Allison looks up at him, tears she hadn't even known were there fall from her eyes. "What–?" she tries to ask, before she has to swallow to get her swollen throat to work properly. Setting her jaw, Allison finishes her question. "What am I supposed to _do _with this?"

Derek tugs the picture from Allison's hand, smoothing it like it's precious to him and folding it back in his wallet. When he looks up again, he says, "I don't know."

Allison nods for a moment before walking away, back toward her car and town and the man who calls himself her father. Except he isn't. He stole her from the hospital and kept her from knowing her real family. And now it's too late. They're all gone except for one.

She hears Derek and Stiles follow her down the trail, talking quietly to one another, but she can't quite make out what they're saying. It grates on her nerves until finally she turns around and stalks up to them, "_What_?"

Derek looks over at Stiles, who nods his head encouragingly and shoves Derek's shoulder as he points to Allison. Derek sighs and asks, "Would you like to come have breakfast and hear some stories about m-_our _family?"

Half of Allison wants to say no, because Derek Hale is her enemy, not her brother. The other half of her says that if she didn't accept this invitation, she might never get another one and she might never know exactly where she came from. The latter half wins out, because she nods. "Don't expect any hugs or anything," she insists, pointing an accusing finger at Derek, who looks genuinely surprised and put out like he hasn't planned on hugging her but now that it's off the table, he resents the missed opportunity.

Stiles laughs and Allison doesn't miss the way he folds his hand into Derek's and jerks his head toward the trail. "Come on. First round's on me."


End file.
